metamorphic
Quartzite
Quartzite (principally SiO2)
Hardness: 7 on Mohs scale; Color: typically white, gray, or pink (this specimen shows a pink/rose hue due to iron oxide impurities); Luster: vitreous to dull; Crystal Structure: non-foliated, granular; Cleavage: none, breaks with a conchoidal fracture.
- Hardness
- 7 on Mohs scale
- Luster
- vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white, gray, or pink (this specimen shows a pink/rose hue due to iron oxide impurities); Luster: vitreous to dull; Crystal Structure: non-foliated, granular; Cleavage: none, breaks with a conchoidal fracture.
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. Under intense heat and pressure, quartz grains recrystallize and fuse together into a dense, hard rock. This specimen likely dates from the Proterozoic to Paleozoic eras.
Uses & applications
Used extensively in road construction as railway ballast and crushed stone, in glass manufacturing, and as decorative stone for countertops, tiles, and landscaping.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks during erosion, often forming the peaks of mountain ranges. It is harder than steel and will scratch glass easily.
Field identification & locations
Identified in the field by its sugary, granular appearance and extreme hardness (it cannot be scratched by a knife). It is found worldwide in mountainous regions or ancient continental shields.
